A while back I asked about this, about a flyback transformer that
sparked from one point on it to another. And the thread turned to
whether it was worth fixing.

But I realize I never did find out why this tv transformer was
different from others. That's more important to me here than fixing
the tv, because this is just a hobby for me and I like to understand
things.

So in other cases where there was sparking I covered the area with a
layer of GE silicone sealant, or cement I think they used to call it.

And then there would be no more sparking. But this time, the spark
moves somewhere else on the flyback. I did this 5 times and every
time the spark moved, on this SONY tv. Sometimes it moved to the
other side of the transformer.

Does that indicate maybe that the high voltage is even higher than
normal? Or that the insulation of the flyback is weaker than normal?


Eventually there was more than a half inch of sealant on some sides,
and the spark moved to where I can hear it loud, but can't even see
it. Either there is a layer of air space I accidentally left (I don't
think so) or it is sparking between the layers without an air space,
or most likely, I think it is sparking between the transformer and the
circuit board.
Thanks.

If you are inclined to email me
for some reason, remove NOPSAM :-)

In a nutshell, the flyback transformer is shot. It's bad, and no amount of
high-voltage dope will fix it.

Flyback transformers do fail, sometimes a bit too regularly. They are
essentially big coils of wire and over time they may start arcing
internally.

A flyback's job is to create the high voltages necessary to make the picture
tube light up. The thick red wire going to the suction cup on the picture
tube can carry 20,000 volts or more, and that's coming from the flyback.
But if the high voltage can find an easier way to get out to ground, it will
do so.

Air has a "breakdown voltage," meaning that an electrical arc will jump
through it if the voltage is high enough. Dry air has a lower breakdown
voltage than moist air; this is one reason why it's so easy to generate
static electricity just by walking across a carpet on a dry day. Since air
is mostly nitrogen, you'll see a deep blue spark in this case.

High-voltage "dope" is a special putty used to prevent electricity from
arcing to the chassis, but as you've witnessed, it can't always work in all
cases.

The only option is to replace the flyback transformer with a new one.

mm wrote:

A while back I asked about this, about a flyback transformer that
sparked from one point on it to another. And the thread turned to
whether it was worth fixing.

But I realize I never did find out why this tv transformer was
different from others. That's more important to me here than fixing
the tv, because this is just a hobby for me and I like to understand
things.

So in other cases where there was sparking I covered the area with a
layer of GE silicone sealant, or cement I think they used to call it.

And then there would be no more sparking. But this time, the spark
moves somewhere else on the flyback. I did this 5 times and every
time the spark moved, on this SONY tv. Sometimes it moved to the
other side of the transformer.

Does that indicate maybe that the high voltage is even higher than
normal? Or that the insulation of the flyback is weaker than normal?


Eventually there was more than a half inch of sealant on some sides,
and the spark moved to where I can hear it loud, but can't even see
it. Either there is a layer of air space I accidentally left (I don't
think so) or it is sparking between the layers without an air space,
or most likely, I think it is sparking between the transformer and the
circuit board.
Thanks.

If you are inclined to email me
for some reason, remove NOPSAM :-)

I've seen them with sparks running all over the surface on all sides,
its due to breakdown not overvoltage. When using HV gloops you've got
to be very thorough about getting every trace of carbonised plastic
off first, else applying gloop is pointless.

The wire insulation will be shot by now, its beyond help. Sparks turn
everything to carbon.


NT

"Matt J. McCullar" writes:

In a nutshell, the flyback transformer is shot. It's bad, and no amount of
high-voltage dope will fix it.

Flyback transformers do fail, sometimes a bit too regularly. They are
essentially big coils of wire and over time they may start arcing
internally.

A flyback's job is to create the high voltages necessary to make the picture
tube light up. The thick red wire going to the suction cup on the picture
tube can carry 20,000 volts or more, and that's coming from the flyback.
But if the high voltage can find an easier way to get out to ground, it will
do so.

Air has a "breakdown voltage," meaning that an electrical arc will jump
through it if the voltage is high enough. Dry air has a lower breakdown
voltage than moist air; this is one reason why it's so easy to generate
static electricity just by walking across a carpet on a dry day. Since air
is mostly nitrogen, you'll see a deep blue spark in this case.

Ooops, other way around. You get static buildup in dry air because there is
lower leakage and the charge can build up.

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Sam Goldwasser wrote:

"Matt J. McCullar" writes:


In a nutshell, the flyback transformer is shot. It's bad, and no amount of
high-voltage dope will fix it.

Flyback transformers do fail, sometimes a bit too regularly. They are
essentially big coils of wire and over time they may start arcing
internally.

A flyback's job is to create the high voltages necessary to make the picture
tube light up. The thick red wire going to the suction cup on the picture
tube can carry 20,000 volts or more, and that's coming from the flyback.
But if the high voltage can find an easier way to get out to ground, it will
do so.

Air has a "breakdown voltage," meaning that an electrical arc will jump
through it if the voltage is high enough. Dry air has a lower breakdown
voltage than moist air; this is one reason why it's so easy to generate
static electricity just by walking across a carpet on a dry day. Since air
is mostly nitrogen, you'll see a deep blue spark in this case.


Ooops, other way around. You get static buildup in dry air because there is
lower leakage and the charge can build up.

yeah, i was scratching my head on that one too!


--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

On Sat, 17 Feb 2007 17:08:54 -0500, mm
wrote:

A while back I asked about this, about a flyback transformer that
sparked from one point on it to another. And the thread turned to
whether it was worth fixing.

But I realize I never did find out why this tv transformer was
different from others. That's more important to me here than fixing
the tv, because this is just a hobby for me and I like to understand
things.

So in other cases where there was sparking I covered the area with a
layer of GE silicone sealant, or cement I think they used to call it.

And then there would be no more sparking. But this time, the spark
moves somewhere else on the flyback. I did this 5 times and every
time the spark moved, on this SONY tv. Sometimes it moved to the
other side of the transformer.

Does that indicate maybe that the high voltage is even higher than
normal? Or that the insulation of the flyback is weaker than normal?


Eventually there was more than a half inch of sealant on some sides,
and the spark moved to where I can hear it loud, but can't even see
it. Either there is a layer of air space I accidentally left (I don't
think so) or it is sparking between the layers without an air space,
or most likely, I think it is sparking between the transformer and the
circuit board.
Thanks.

If you are inclined to email me
for some reason, remove NOPSAM :-)

You could have an environmental problem. Something (dust, vapor, UV
light, high temperature, high altitude, suspended water droplets,
etc..) in the atmosphere that is either attracted to the coil and
causing some ionization and breakdown, or attacking the insulation on
the coil.

Or just a faulty coil.

It is usually better to over react to a corona problem, a little bit
of carbon tracking from a previous breakdown can cause the next.
--

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On Sun, 18 Feb 2007 06:14:28 GMT, "Matt J. McCullar"
wrote:

In a nutshell, the flyback transformer is shot. It's bad, and no amount of
high-voltage dope will fix it.

Flyback transformers do fail, sometimes a bit too regularly. They are
essentially big coils of wire and over time they may start arcing
internally.

A flyback's job is to create the high voltages necessary to make the picture
tube light up. The thick red wire going to the suction cup on the picture
tube can carry 20,000 volts or more, and that's coming from the flyback.
But if the high voltage can find an easier way to get out to ground, it will
do so.

Air has a "breakdown voltage," meaning that an electrical arc will jump
through it if the voltage is high enough. Dry air has a lower breakdown
voltage than moist air; this is one reason why it's so easy to generate
static electricity just by walking across a carpet on a dry day. Since air
is mostly nitrogen, you'll see a deep blue spark in this case.

High-voltage "dope" is a special putty used to prevent electricity from
arcing to the chassis, but as you've witnessed, it can't always work in all
cases.

The only option is to replace the flyback transformer with a new one.

As I said, I don't want to get sidetracked like last time by fixing
the tv.

But I appreciate the rest of your reply.



If you are inclined to email me
for some reason, remove NOPSAM :-)

On 18 Feb 2007 00:18:40 -0800, wrote:


Eventually there was more than a half inch of sealant on some sides,
and the spark moved to where I can hear it loud, but can't even see
it. Either there is a layer of air space I accidentally left (I don't
think so) or it is sparking between the layers without an air space,
or most likely, I think it is sparking between the transformer and the
circuit board.
Thanks.

I've seen them with sparks running all over the surface on all sides,
its due to breakdown not overvoltage.

Great. Thanks. That's what I wanted to know.

When using HV gloops you've got
to be very thorough about getting every trace of carbonised plastic
off first, else applying gloop is pointless.

Everything looked very normal, very uniform, including where the
sparks were. I guess I should have tried scraping off the top layer,
but maybe

The wire insulation will be shot by now, its beyond help. Sparks turn
everything to carbon.

It's strange. I've been using it as a monitor temporarily, and once
it sparked every 10 seconds for 4 or 5 times, but most of the time it
goes a half hour or hour with no sparks. (It's easy to notice when it
sparks, and hard to recall when it doesn't.) When I'm done using it
as a monitor, I'll see how it's going. Maybe if it gets worse, I'll
take off the silicone and see if I can do a better job putting it on.

If you are inclined to email me
for some reason, remove NOPSAM :-)

On Sun, 18 Feb 2007 15:20:13 -0500, default
wrote:

Eventually there was more than a half inch of sealant on some sides,
and the spark moved to where I can hear it loud, but can't even see
it. Either there is a layer of air space I accidentally left (I don't
think so) or it is sparking between the layers without an air space,
or most likely, I think it is sparking between the transformer and the
circuit board.
Thanks.

You could have an environmental problem. Something (dust, vapor, UV
light, high temperature, high altitude, suspended water droplets,
etc..) in the atmosphere that is either attracted to the coil and
causing some ionization and breakdown, or attacking the insulation on
the coil.

So, a third possibility. Thanks.

Or just a faulty coil.

It is usually better to over react to a corona problem, a little bit
of carbon tracking from a previous breakdown can cause the next.

I've done better in the past. It looks something like the Elephant
Man's head now.
--


If you are inclined to email me
for some reason, remove NOPSAM :-)